Fix #790: torrent client URL without http:// scheme fails to connect

A bare host like '192.168.1.5:8080' or 'qbittorrent.lan:8080' (no scheme)
is what users naturally type, but requests then raises 'No connection
adapters were found for ...' — it can't pick an http/https adapter, and a
bare host:port even gets misparsed as scheme=host. This surfaced as the
generic 'qbittorrent probe failed' with a 'login error: No connection
adapters were found' in the logs.

Add normalize_client_url() in torrent_clients/base: default a missing scheme
to http:// (+ trim trailing slash), and route all three adapters'
_load_config through it. Transmission normalizes the base before appending
/transmission/rpc.

Tests: normalizer unit cases + per-adapter regression (bare host -> http://).

Note: usenet adapters (sabnzbd/nzbget) share the same pattern and need the
same treatment in a follow-up.

core/torrent_clients/base.py

@@ -20,6 +20,24 @@ from dataclasses import dataclass
 from typing import List, Optional, Protocol, runtime_checkable
 
 
+def normalize_client_url(raw: str) -> str:
+    """Clean a user-entered WebUI URL into something ``requests`` accepts.
+
+    Users routinely type a bare host like ``192.168.1.5:8080`` or
+    ``qbittorrent.lan:8080`` with no scheme. ``requests`` then raises
+    "No connection adapters were found for '...'" because it can't pick an
+    http/https adapter (a bare ``host:port`` even gets misparsed as
+    ``scheme=host``). Default a missing scheme to ``http://`` and trim a
+    trailing slash. Empty input passes through unchanged.
+    """
+    url = (raw or '').strip()
+    if not url:
+        return ''
+    if '://' not in url:
+        url = 'http://' + url
+    return url.rstrip('/')
+
+
 @dataclass
 class TorrentStatus:
     """Adapter-uniform view of one torrent's live state.

core/torrent_clients/deluge.py

@@ -20,7 +20,7 @@ from typing import Any, List, Optional
 import requests as http_requests
 
 from config.settings import config_manager
-from core.torrent_clients.base import TorrentStatus
+from core.torrent_clients.base import TorrentStatus, normalize_client_url
 from utils.logging_config import get_logger
 
 logger = get_logger("torrent.deluge")
@@ -67,7 +67,7 @@ class DelugeAdapter:
         self._load_config()
 
     def _load_config(self) -> None:
-        self._url = (config_manager.get('torrent_client.url', '') or '').rstrip('/')
+        self._url = normalize_client_url(config_manager.get('torrent_client.url', ''))
         # Deluge's WebUI auth uses a single password, not username+password.
         # We accept whichever field the user filled in — keeps the UI uniform.
         self._password = (

core/torrent_clients/qbittorrent.py

@@ -18,7 +18,7 @@ from typing import List, Optional
 import requests as http_requests
 
 from config.settings import config_manager
-from core.torrent_clients.base import TorrentStatus
+from core.torrent_clients.base import TorrentStatus, normalize_client_url
 from utils.logging_config import get_logger
 
 logger = get_logger("torrent.qbittorrent")
@@ -64,7 +64,7 @@ class QBittorrentAdapter:
         self._load_config()
 
     def _load_config(self) -> None:
-        self._url = (config_manager.get('torrent_client.url', '') or '').rstrip('/')
+        self._url = normalize_client_url(config_manager.get('torrent_client.url', ''))
         self._username = config_manager.get('torrent_client.username', '') or ''
         self._password = config_manager.get('torrent_client.password', '') or ''
         self._category = config_manager.get('torrent_client.category', 'soulsync') or 'soulsync'

core/torrent_clients/transmission.py

@@ -18,7 +18,7 @@ from typing import List, Optional
 import requests as http_requests
 
 from config.settings import config_manager
-from core.torrent_clients.base import TorrentStatus
+from core.torrent_clients.base import TorrentStatus, normalize_client_url
 from utils.logging_config import get_logger
 
 logger = get_logger("torrent.transmission")
@@ -57,7 +57,7 @@ class TransmissionAdapter:
         self._load_config()
 
     def _load_config(self) -> None:
-        url = (config_manager.get('torrent_client.url', '') or '').rstrip('/')
+        url = normalize_client_url(config_manager.get('torrent_client.url', ''))
         # Transmission's RPC endpoint is always /transmission/rpc — if the
         # user pasted a bare host URL, append it. If they pasted the full
         # /transmission/rpc URL, leave it.

tests/test_torrent_client_adapters.py

@@ -263,6 +263,58 @@ def test_transmission_normalises_bare_host_to_rpc_path() -> None:
     assert adapter._url == 'http://host:9091/transmission/rpc'
 
 
+# ---------------------------------------------------------------------------
+# URL scheme normalization (#790)
+# ---------------------------------------------------------------------------
+
+
+def test_normalize_client_url_prepends_http_when_scheme_missing() -> None:
+    from core.torrent_clients.base import normalize_client_url
+    # The exact shapes users type: bare IP:port, bare DNS name:port, bare host.
+    assert normalize_client_url('192.168.1.5:8080') == 'http://192.168.1.5:8080'
+    assert normalize_client_url('qbittorrent.lan:8080') == 'http://qbittorrent.lan:8080'
+    assert normalize_client_url('myhost') == 'http://myhost'
+
+
+def test_normalize_client_url_preserves_existing_scheme_and_trims() -> None:
+    from core.torrent_clients.base import normalize_client_url
+    assert normalize_client_url('http://host:8080') == 'http://host:8080'
+    assert normalize_client_url('https://host') == 'https://host'
+    assert normalize_client_url('  http://host:8080/  ') == 'http://host:8080'
+    assert normalize_client_url('') == ''
+    assert normalize_client_url(None) == ''
+
+
+def test_qbit_load_config_defaults_scheme_for_bare_host() -> None:
+    """Regression #790: a bare ``host:port`` config (no scheme) must become an
+    http:// URL. Otherwise requests can't pick an adapter and raises
+    'No connection adapters were found for ...', which surfaced to the user as
+    a generic 'qbittorrent probe failed'."""
+    adapter = QBittorrentAdapter.__new__(QBittorrentAdapter)
+    import threading
+    adapter._session = None
+    adapter._session_lock = threading.Lock()
+    with patch('core.torrent_clients.qbittorrent.config_manager') as cm:
+        cm.get.side_effect = lambda key, default='': {
+            'torrent_client.url': '192.168.1.5:8080',
+        }.get(key, default)
+        adapter._load_config()
+    assert adapter._url == 'http://192.168.1.5:8080'
+
+
+def test_deluge_load_config_defaults_scheme_for_bare_host() -> None:
+    adapter = DelugeAdapter.__new__(DelugeAdapter)
+    import threading
+    adapter._session = None
+    adapter._session_lock = threading.Lock()
+    with patch('core.torrent_clients.deluge.config_manager') as cm:
+        cm.get.side_effect = lambda key, default='': {
+            'torrent_client.url': 'deluge.lan:8112',
+        }.get(key, default)
+        adapter._load_config()
+    assert adapter._url == 'http://deluge.lan:8112'
+
+
 def test_transmission_session_id_renegotiation() -> None:
     """Transmission rejects the first call with 409 and a fresh
     ``X-Transmission-Session-Id`` header; the adapter must store it